1. Field of the Invention
The present invention relates to radiation converters and, more particularly, to an apparatus for converting infrared radiation to visible radiation or electric signals.
2. Description of Related Art
The conversion of infrared (IR) radiation to proportionate electrical signals or visible radiation is of great importance in military, industrial and medical imaging. In the art of IR converters and IR imaging, however, there are no known photoemissive materials for infrared wavelengths. Thus, it is necessary to convert IR wavelengths into electrical signals or wavelengths that can be detected or visually perceived.
In current infrared conversion systems a number of different photoconductive and thermally sensitive screens have been placed on vidicon-type imagers. These infrared conversion systems generally have been operated at or above ambient temperature because of the inability to cool the screen and/or prevent condensation on the screen while cold. Operation at such elevated temperatures degrades the performance of the conversion system as a whole.
Some single element infrared converters have been fabricated which utilize an infrared semiconductor as the active layer in a Schottky barrier diode cold cathode. These devices tend to be unsatisfactory because they are limited to operation at temperatures too warm for infrared detectors. Reducing the operating temperatures of these IR converters promotes the formation of surface condensation, thus degrading their performance. To prevent condensation, vacuum enclosures or other hemetically sealed enclosures are required.
Conventional infrared converters also involve the use of complex mechanisms and supporting electronics. The cost of these infrared converters limit their widespread use.
In recent years, much work has been done to produce infrared focal plane arrays for converting infrared radiation into proportionate electrical signals. Existing infrared focal plane arrays require special fabrication techniques reducing production volume and increasing production cost.
Accordingly, the present invention provides an IR converter for converting IR radiation into electrical signals or visible radiation that is mechanically and electrically simple and that can be manufactured at a relatively low cost.
A further object of the present invention is to provide an IR converter that can be easily fabricated using conventional techniques.
A still further object of the present invention is to provide an IR converter that can operate effectively over a large range of temperature conditions.
Additional objects and advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.